[v3,1/3] crypto: introduce acomp_is_sleepable to expose if comp drivers might sleep

From: Barry Song <v-songbaohua@oppo.com>

Almost all CPU-based compressors/decompressors are actually synchronous
though they support acomp APIs. While some hardware has hardware-based
accelerators to offload CPU's work such as hisilicon and intel/qat/,
their drivers are working in async mode.
Letting acomp's users know exactly if the acomp is really async will
help users know if the compression and decompression procedure can
sleep.
Generally speaking, async and sleepable are semantically similar but
not equal. But for compress drivers, they are actually equal at least
due to the below facts.
Firstly, scompress drivers - crypto/deflate.c, lz4.c, zstd.c, lzo.c
etc have no sleep. Secondly, zRAM has been using these scompress
drivers for years in atomic contexts, and never worried those drivers
going to sleep.

Signed-off-by: Barry Song <v-songbaohua@oppo.com>
Tested-by: Chengming Zhou <zhouchengming@bytedance.com>
---
 crypto/acompress.c         | 8 ++++++++
 include/crypto/acompress.h | 9 +++++++++
 2 files changed, 17 insertions(+)

On Tue, Feb 20, 2024 at 12:07 PM Barry Song <21cnbao@gmail.com> wrote:
>
> On Mon, Feb 19, 2024 at 5:25 PM Herbert Xu <herbert@gondor.apana.org.au> wrote:
> >
> > On Sat, Feb 17, 2024 at 05:51:00PM +1300, Barry Song wrote:
> > .
> > > diff --git a/crypto/acompress.c b/crypto/acompress.c
> > > index 1c682810a484..fa15df394a4c 100644
> > > --- a/crypto/acompress.c
> > > +++ b/crypto/acompress.c
> > > @@ -152,6 +152,14 @@ struct crypto_acomp *crypto_alloc_acomp_node(const char *alg_name, u32 type,
> > >  }
> > >  EXPORT_SYMBOL_GPL(crypto_alloc_acomp_node);
> > >
> > > +bool acomp_is_sleepable(struct crypto_acomp *acomp)
> > > +{
> > > +     struct crypto_tfm *tfm = crypto_acomp_tfm(acomp);
> > > +
> > > +     return tfm->__crt_alg->cra_type == &crypto_acomp_type;
> > > +}
> > > +EXPORT_SYMBOL_GPL(acomp_is_sleepable);
> >
> > Just because something is of acomp_type it doesn't mean that it's
> > async.  You should be testing the algorithm flags.
>
> I guess I got your point, drivers using acomp framework might actually
> be SYNC if they don't set CRYPTO_ALG_ASYNC.
>
> >
> > So introduce a helper crypto_acomp_get_flags (see the similar
> > helper crypto_skcipher_get_flags) and test it against CRYPTO_ALG_ASYNC.
>
> On the other hand, some drivers which are actually ASYNC, are lacking
> CRYPTO_ALG_ASYNC for example:
>
> diff --git a/drivers/crypto/hisilicon/zip/zip_crypto.c
> b/drivers/crypto/hisilicon/zip/zip_crypto.c
> index c650c741a18d..94e2d66b04b6 100644
> --- a/drivers/crypto/hisilicon/zip/zip_crypto.c
> +++ b/drivers/crypto/hisilicon/zip/zip_crypto.c
> @@ -591,6 +591,7 @@ static struct acomp_alg hisi_zip_acomp_deflate = {
>         .base                   = {
>                 .cra_name               = "deflate",
>                 .cra_driver_name        = "hisi-deflate-acomp",
> +               .cra_flags              = CRYPTO_ALG_ASYNC,
>                 .cra_module             = THIS_MODULE,
>                 .cra_priority           = HZIP_ALG_PRIORITY,
>                 .cra_ctxsize            = sizeof(struct hisi_zip_ctx),
> diff --git a/drivers/crypto/intel/iaa/iaa_crypto_main.c
> b/drivers/crypto/intel/iaa/iaa_crypto_main.c
> index dfd3baf0a8d8..91adf9d76a2e 100644
> --- a/drivers/crypto/intel/iaa/iaa_crypto_main.c
> +++ b/drivers/crypto/intel/iaa/iaa_crypto_main.c
> @@ -1916,6 +1916,7 @@ static struct acomp_alg iaa_acomp_fixed_deflate = {
>         .base                   = {
>                 .cra_name               = "deflate",
>                 .cra_driver_name        = "deflate-iaa",
> +               .cra_flags              = CRYPTO_ALG_ASYNC,
>                 .cra_ctxsize            = sizeof(struct iaa_compression_ctx),
>                 .cra_module             = THIS_MODULE,
>                 .cra_priority           = IAA_ALG_PRIORITY,
> diff --git a/include/crypto/acompress.h b/include/crypto/acompress.h
> index 574cffc90730..5b10bd075a07 100644
> --- a/include/crypto/acompress.h
> +++ b/include/crypto/acompress.h
> @@ -160,6 +160,11 @@ static inline void acomp_request_set_tfm(struct
> acomp_req *req,
>         req->base.tfm = crypto_acomp_tfm(tfm);
>  }
>
> +static inline u32 crypto_acomp_get_flags(struct crypto_acomp *tfm)
> +{
> +       return crypto_tfm_get_flags(crypto_acomp_tfm(tfm));
> +}

This seems to be wrong. we are expecting cra_flags not crt_flags. should be
the below?

diff --git a/include/crypto/acompress.h b/include/crypto/acompress.h
index 574cffc90730..07bd8f6bc79a 100644
--- a/include/crypto/acompress.h
+++ b/include/crypto/acompress.h
@@ -160,6 +160,11 @@ static inline void acomp_request_set_tfm(struct
acomp_req *req,
        req->base.tfm = crypto_acomp_tfm(tfm);
 }

+static inline u32 crypto_acomp_get_alg_flags(struct crypto_acomp *tfm)
+{
+       return crypto_tfm_alg_flags(crypto_acomp_tfm(tfm));
+}
+
 static inline struct crypto_acomp *crypto_acomp_reqtfm(struct acomp_req *req)
 {
        return __crypto_acomp_tfm(req->base.tfm);
diff --git a/include/linux/crypto.h b/include/linux/crypto.h
index b164da5e129e..811bfaf8b6f8 100644
--- a/include/linux/crypto.h
+++ b/include/linux/crypto.h
@@ -467,6 +467,11 @@ static inline unsigned int
crypto_tfm_alg_blocksize(struct crypto_tfm *tfm)
        return tfm->__crt_alg->cra_blocksize;
 }

+static inline unsigned int crypto_tfm_alg_flags(struct crypto_tfm *tfm)
+{
+       return tfm->__crt_alg->cra_flags;
+}
+
 static inline unsigned int crypto_tfm_alg_alignmask(struct crypto_tfm *tfm)
 {
        return tfm->__crt_alg->cra_alignmask;

> +
>  static inline struct crypto_acomp *crypto_acomp_reqtfm(struct acomp_req *req)
>  {
>         return __crypto_acomp_tfm(req->base.tfm);
>
>
> Herbert, Is the above code what you would prefer?
>
> >
> > Cheers,
> > --
> > Email: Herbert Xu <herbert@gondor.apana.org.au>
> > Home Page: http://gondor.apana.org.au/~herbert/
> > PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
>
Thanks
Barry